Not sure how useful these websites are but they seem to imply that your steel sword up there was used as currency for major transactions by the Kuba tribe of Southeast Congo.
http://www.hamillgallery.com/SITE/Weapons.html
http://www.forafricanart.com/Kuba_ep_39-1.html
As for storing, a shelf is fine so long as it isn't too moist or damp. For antiques they look like they're in fairly good condition so whatever you're doing seems to be working.
Bookmarks